One very prevalent form of health care therapy is infusion or intravenous ("I.V.") therapy whereby fluids possessing desired medication or other characteristics are infused into a patient over varying lengths of time. To practice this infusion therapy frequently a connection needs to be made between components for the transfer of fluid between the two components, along a fluid passageway and eventually to a patient. As an example, administration sets are widely used to administer liquids parenterally to a patient and other medical devices are connected to the administration set to provide the proper administration.
One widely used connector for making a connection between medical devices to establish a fluid passageway is a luer connection assembly. In the luer connection assembly, a male luer tip component or fitting having a frustoconical shape is inserted into a female luer component or fitting having a frustoconical shaped receiving cavity and opposing conical surfaces come into contact to form a sealed friction fit.
Until the connection is made, the passageway through each of the luer fittings and into the lumen of a component attached to the luer fitting is open to the environment. This lumen and the passageway through the luer connectors form a portion of the fluid passageway and must be sterile prior to use and then sealed against microbial ingress during use. Thus, these connection assemblies and the associated components are packaged in sterile packaging and the connections are typically made just prior to establishing fluid communication with a patient's venous system.
There are two general types of luer connection assemblies. One type is generally referred to as the luer slip where the connection is maintained by the friction fit between the male luer tip and female luer component. The other type is generally referred to as a luer lock connection whereby the male luer tip is encircled by an annular flange having a threaded internal surface. The female component includes a corresponding thread formed about the outer surface. Engaging the threaded flange to the threaded outside surface establishes the connection between the male luer tip and female component while preventing accidental disconnects.
To insure a universal luer connections among components provided by a multitude of manufacturers, luer connection assemblies are manufactured to comply with universal standards. Very important sets of standards such as ANSI and ISO standards. These standards includes standard dimensions for male slip and luer lock assemblies. Among these dimensional standards are standards which define the spacing or clearance between the annular locking flange and the male luer tip. Thus any female connection device configured to establish a connection to a standard male luer lock must be able to engage the luer tip and locking flange within this clearance or spacing.
Other standards in the ISO standards include several performance requirements for luer connections. One such requirement is that after a luer lock type connection is made, to prevent inadvertent disconnection, the luer connection should resist an axial removal force of 8 pounds and unscrewing torque less than 2.8 in/oz without disconnection. Luer connections should also hold a seal against 45 psi after a connection torque of 16 in/oz has been applied. In standard luer connections this resistance and sealing is supplied by the friction between the opposing conical surfaces.
Once a component of l.V. therapy is placed in fluid communication with the body, the fluid passageway should be sealed from the environment to prevent contamination and this passageway should also be sealed so as to not allow any leakage of bodily fluids into the environment. However, most therapies require periodic access to the fluid passageway. Because the portion of the fluid passageway through a female luer connection component is open to the environment, these components will not form a sealed connection to the fluid passageway after the fluid passageway is placed in fluid communication with the body.
In one prevalent example of intravenous therapy, fluid containing a drug in solution is injected into a primary flow of fluid from an l.V. solution container through an administration set to a catheter extending within a vein. The drug containing fluid may be injected from a syringe, secondary medication set or the like, into the set where it mixes with the flowing fluid. In another prevalent example, fluid is injected directly into or withdrawn from a catheter extending within the body. In addition the catheters are flushed periodically to maintain patency by the injection of small amounts of saline or heparin.
As can be appreciated, it is highly desirable to maintain catheters and administration sets in service as long as possible without compromising the safety of the patient. Replacement of catheters and sets is time consuming and expensive. Therefore over the period of time of use of a set or catheter there may be many connections and disconnects. For example, there may be over 100 connections and disconnects to a connection site on a catheter or set before the catheter or set is replaced. In addition a connection may be made and that connection maintained for an extended period of time before disconnection. For example a connection may be made for up to seven days of "indwell" and yet the connection should still be capable of accepting intermediate and subsequent connections and disconnects without allowing leakage to the environment.
Another highly desirable attribute of a connector is the ability for such a connector to seal against pressurized fluid found within a set or for the connector to possess a certain leak pressure in excess of a desired pressure. For example it is desirable for a connector to have a leak pressure which is in excess of 20 p.s.i. for a short period of time such as when a bolus administration of drug is injected into a set and a leak pressure in excess of 6 p.s.i. of continuous pressure during infusion of medication.
In addition, a connector may be exposed to negative pressure particularly when such connector is located upstream of an inlet of an intravenous pump. Failure to prevent aspiration through a connector when the connector is exposed to negative pressure may lead to an aspiration of air and/or microbes into the fluid passageway.
Depending on the application, many other features may be desirable. Dead spaces within any connector which cannot be "flushed" should be minimized or eliminated as they may form an environment for microbial growth. Also, priming volume for the connector should be minimized.
Because intravenous therapy is practiced on a worldwide basis and millions of connection sites are used every year and the costs of components used in such therapy are a factor in the cost of therapy, any desired connector should be capable of being manufactured at high speeds and low cost. Generally the lower the number of parts making up a component, the lower the number of molds and high speed assembly devices both of which generally translate to lower capital expenditures and therefore lower costs.
On the other hand, whatever the connector configuration, it is highly desirable that the connector be capable of low defect manufacture. Even a small number of failure is generally unacceptable when a single failure may put a patient or health care provider at risk.
Moreover, it is also highly desirable that any surfaces around an inlet into a connector be able to be swabbed or otherwise disinfected. Typically unbroken or smooth surfaces facilitate swabbing and other disinfecting techniques.
As mentioned previously, although luer connectors are widely found in the medical environment such connections are generally not acceptable when many of the above described requirements need to be satisfied. This is primarily due to the fact that the opening through the luer connector is not sealed so that upon disconnection the opening and the fluid passageway are open to the environment which would pose a health hazard to the patient.
Another factor which prevents use of luer connection assemblies in administration sets or injection sites is the inability for such a connector to seal against the pressurized fluid found within a set unless that connector is sealed or connected to a mating connector. The opening in a luer fitting will obviously allow such a pressurized fluid to leak.
To allow the sealed connections and disconnects to a fluid passageway extending in a set or catheter, on many sets there are one or more injection sites having a solid resilient septum in a housing which are placed on the set or catheter. A sharpened needle is used to penetrate the septum to provide a connection to the fluid passageway. Although such connections possess many of the desired characteristics for sealed connections, the sharpened needles pose a needlestick hazard.
To combat the needlestick hazard, one embodiment of a needleless system has been developed which utilizes a resealable septum formed with a slit and compressed within a housing. These needleless systems performed quite well; however, the septum can not be penetrated with a male luer tip and thus a blunt cannula is utilized having a diameter smaller than a male luer tip. If the device to which a connection needs to be made has a luer connector, these blunt cannula are generally attached to the luer fitting. The requirement of the blunt cannula potentially increases the costs of using these types of connectors.
Another type of needleless systems use connectors which are constructed to establish a connection directly with the male luer tip whether such luer tip forms a part of a luer slip or a luer lock. However connections which are to be established with a male luer tip in a manner similar to a luer lock connection described above must be capable of fitting within the standard spacing between a luer tip and locking flange and should also meet other standards which have been set out for such connections.
Examples of these systems' connectors to establish a connection directly with a male luer tip are shown in U.S. Pat. No. 5,685,866, the disclosure of which is incorporated by reference herein. These connectors appear to all possess shortcomings which hinder widespread acceptance by medical practitioners. In general, all of these devices perform in an inferior manner when measured relative to the desirable qualities for connector devices discussed above and also in comparison to the performance standards of a injection site for a sharpened needle and resilient septum, or a blunt cannula and pre-slit resilient septum
For example, several connectors utilize a resilient boot or other seal which is placed within a housing and collapsed by the introduction of a male luer tip. Upon removal of the tip, such collapsing boots must then recover to reseal the connection. Many or these boots stick in the collapsed position which leads to leaking. In addition these moving parts present an interface between the movable boot and housing into which fluid may flow and collect and such collected fluids form a fertile environment for microbial growth, and recessed surfaces and gaps are hard to disinfect. Moreover, the spikes act as flow restrictors and may impart severe turbulence to fluid as it flows through the openings in the spike. Furthermore, after withdrawal of a male luer tip the boots may not recover quickly enough to seal the entrance through the connector and the fluid passageway may be briefly exposed to the environment.
One type of such luer tip connectors has a spike within the housing which penetrates a collapsing boot. The spike has openings proximate an end adjacent the boot and form an internal passageway for the flow of fluid which is opened when the spike penetrates the collapsed boot and spreads the slit. Upon recovery, any slit or opening in the boot must reseal. However, the spike design has exhibited unsatisfactory leakage after a number of connects and disconnects which does not provide for extended use of a set or catheter.
In addition, these connectors have a multitude of parts which increases manufacturing costs and opportunities for malfunction. These designs also produce a connector having voids which cannot be flushed such that stagnant fluid may collect. Moreover, several of these device have potential passageways from voids within the housing but outside the primary fluid passageway, into the primary fluid passageway which may allow any microbial growth within the housing to enter the fluid passageway. Also the interface between the housing and boot is difficult to swab when the boot is in the uncompressed position.
A device described in U.S. Pat. No. 5,616,130, the disclosure of which is incorporated by reference herein, utilizes an elongated cam to spread open a slit in a collapsing boot, and would appear to possess several of the shortcomings of the spike and boot designs described above.
It is generally not a problem for the boot connectors to have ends which engage the male tip and locking flange on a standard luer lock. The sealing mechanism is below the end of the luer tip when the tip is engaged to the connector, thus there is a large amount of flexibility in the configuration of the end of the connector housing which engages the male luer lock.
To overcome many of these deficiencies, needleless connections which utilize a preslit septum as one of the components were developed. These connectors establish a connection with the penetration of the slit in the septum by the luer tip. One such connector is shown and described in U.S. Pat. No. 5,578,059, the disclosure of which is incorporated by reference herein. In the disclosed valve, a resilient preslit septum is utilized to form an environmental barrier. The septum is sealingly captured or held to the housing by having a lower flange which is pinched between a retainer and housing. It appears that the radially extending portion having a slit is maintained in position by the column strength of an outer axially extending cylindrical portion extending upward from the lower flange. However the septum appears not to be capable of sealing against the pressurized fluid found in a set. Thus the valve uses a second lower check type valve to seal against the pressure.
To satisfy ISO dimensional standards and torque removal resistance standards the outer portion of the retainer is formed with tapered threads so that the connection to a luer lock's straight thread design is similar to a standard NPTF/NPSI connection. The tapered thread design extends over the end of the housing that engages the threads on a male luer lock. Such a thread design may produce too rapid an increase in engaging force during the connection which may lead to a lock up of the luer lock to the connector.
Such a device suffers from several other drawbacks. The valve includes a number of components to make up the housing, the environmental valve and check valve, and this high number of components increases manufacturing costs. In addition, maintaining the septum in position by the column strength of the axially extending portion of the septum forces that portion to have a relatively large thickness. Thus for the septum, the axially extending wall and surrounding housing to fit within the clearance between the luer tip and the locking flange upon penetration of a male luer tip to a desired depth, the housing must be thinned. Such a thinned housing may fracture upon repeated connections and disconnects.
A second connector is described in U.S. Pat. No. 5,533,708, the disclosure of which is incorporated by reference herein. This connector also utilizes a preslit septum which is supported on an axially extending column having sufficient thickness to support the septum upon introduction of the male luer tip. To further provide sufficient column strength the axially extending portion is also formed with a specific tapered shape including a thickened lower portion. To seal the slit during introduction and removal of a luer tip, the underside of the pre-slit radial portion of the septum is formed with biasing ribs.
This connector also uses a retainer which pinches a lower radial flange to sealingly fix the septum to the housing. Thus the connector includes three separate pieces. In addition the thickened axially extending portion of the septum forces the retainer to be thinned such that to presumably supply strength to the retainer the stated preferred material for the retainer is metal which increases manufacturing costs. In addition it is believed that such valves will not exhibit satisfactory leak pressure after long periods of indwell, likely due to compression set of the septum material due to a perceived high level of compression of the septum material between the tip and retainer.
To supply the necessary unscrewing resistance, the retainer is tapered outward proximate the end to establish a frictional engagement with the threads on a male luer lock.
Therefore, it is a main object of the invention to overcome those disadvantages of the prior art which prevent widespread acceptance of needleless valves which do not require a blunt cannula.
There are other secondary objects, one or more if satisfied may promote market acceptance but satisfaction of each may not be necessary. One object of the present invention is to provide a needless connector fitting which may be actuated by a male luer tip without using a sharpened needle or an adapter such as a blunt cannula or the like. A related object is to provide a connector which may engage a standard luer lock fitting. A further related object is to provide such a connector which may be coupled to a standard male luer lock and complies as much as possible with ISO and ANSI standards for luer connectors.
Another object of the present invention is to provide a connector which possess sufficient strength to avoid cracking or fracture.
It is a further object of the present invention to provide a connector device which utilizes a minimum number of parts and therefore minimizes opportunity for malfunction.
It is another object of the present invention to provide a connector device which is capable of providing for a large number of connections and disconnects while maintaining the ability to seal against fluids under pressures typically found in an administration set. A related object is to provide such a connector which is capable of providing a minimum of 100 connects and disconnects without compromising the performance.
It is yet a further object of the present invention to provide a connector which upon a disconnection, maintains a leak pressure of 6 psi. constant pressure and 20 psi transient pressure after 4 days of indwell.
It is a further object of the present invention to provide a connector which is capable of high speed manufacturing. It is a related object of the present invention to provide a connector which may be manufactured with a very low number of potential defects.
It is yet another object of the present invention to provide a connector which minimizes voids which cannot be flushed in which stagnant fluid can collect to form a media for microbial growth. It is a is related object of the present invention to provide a connector which forms a sealed fluid path such that a minimum number of microbes enter the fluid path during operation using aseptic techniques. It is a further related object to provide a connector which requires a low priming volume.
It is still a further object of the present invention to provide a connector which minimizes or eliminates flow restrictions for the flow of fluid through the connector. In addition it is an object to provide a connector having smooth unbroken surfaces about any inlet to facilitate aseptic techniques.
It is yet another object of the present invention to provide a connector which forms a continuous closed system which seals the fluid passageway from the environment during and after insertion of a male luer tip and instantaneously after withdrawal of the luer tip.